As others, I'd certainly like to be able to perform arbitrary rotations. Working with photos to extract, eg, document contents from a scanned image, and displaying a graphical "busy" spinner, are the use cases I have handled before.
If performance was too poor, I'd be more inclined to look at how to improve performance in Emacs than to abandon the approach in favor of a large number of barely changed images. That would, after all, make life better for everyone, and I have confidence that it *would* be possible to make that efficient enough to work.
After all, I don't need 60FPS rendering of this, and that is definitely achievable for vastly more complex 2D and 3D layouts on the display layers on all the platforms Emacs supports, thanks to browsers among other tools.